|MP+, PPP Ascend's Multilink Protocol Plus|
|Protocol type:||PPP network layer protocol.|
MP+ is used for managing multiple data connections that are bundled by MP.
MP+ is a control protocol for managing multiple data links that are bundled by MP.
MP+ is an extension to MP that adds an inband control channel to provide a new level of session management and control.
MP+ also allows remote device management of (unconfigured) systems. This feature allows a network operations center to dial into an unconfigured system and remotely manage it, before ethernet interface, IP address, and other LCP and system configuration information is entered. (This does require local configuration of the WAN interfaces to the extent required to answer an incoming call).
The features of MP+ include:
- Ability to negotiate to add and subtract channels when bandwidth needs change.
- Phone number management so calling stations need not know every possible number; answering stations can manage their own resources.
- A simple remote management interface.
To perform the above functions MP+ is split into a call management layer and a reliable delivery layer. The call management layer is the source and sink of MP+ control messages. The reliable delivery layer adds a simple acknowledge and retry mechanism.
MP+ only takes network bandwidth when in the process of performing a user request, e.g. adding and subtracting bandwidth.
MP+ is also negotiated during initial LCP option negotiation. A system indicates to its peer that it is willing to do MP+ by sending the MP+ option as part of the initial LCP option negotiation. The MP+ option MUST NOT be negotiated unless MP is also negotiated. When used, MP+ adds a virtual unit-to-unit control channel.
A peer may elect to:
- Acknowledge both the MP and MP+ options, indicating that both MP and MP+ will be used.
- Acknowledge the MP option and reject the MP+ option. Operation will fall back to MP.
- Reject both options. Standard PPP will be used for this connection.
PPP with MP and MP+. When MP+ is negotiated at LCP startup, the same procedures are followed as when MP is negotiated alone. The MP+ LCP option is negotiated to indicate the ability to use the MP+ feature. The first connection between endpoints causes the MP+ process to be started for the connection.
[RFC 1934] Ascend's Multilink Protocol Plus (MP+).